This invention relates to a downflow-type spin dryer used for drying semiconductor substrates and the like.
Downflow spin dryers are used, for example, for drying wafers in the manufacture of semiconductor chips. In a downflow spin dryer, as shown in FIG. 4, a cradle 41 for accommodating items to be dried is fitted into a rotor 42, the rotor 42 is rotated in the direction of arrow A by driving means (not shown), and the items to be dried are dried by centrifugal force created by the rotation and air sucked in through an air inlet 43 and discharged through an air outlet 44 along with this rotation. A filter is fitted over the entire area of the air inlet 43 to prevent incursion of dust into the dryer, and a cover 45 is fitted to the main unit 46 during drying of the items to be dried.
Part of this downflow spin dryer is shown in the enlarged view of FIG. 5, in which elements which are the same as those in FIG. 4 are denoted by the same reference numerals. When drying wafers, wafers n are accommodated so as to be oriented parallel to the rotational direction A of the rotor 42, as shown in FIG. 5. The cradle 41 is provided with mounting holes 41a and 41b, and the rotor 42 is provided with mounting holes 42a and 42b. The mounting holes 41a and 42a and the mounting holes 41b and 42b are fixed together, for example, by screws, and the cradle 41 is thereby mounted in the rotor 42.
The cradle 41 is shown mounted in the rotor 42 in FIG. 6. In the state shown in FIG. 6, the rotor 42 rotates. Because the mounting holes 41a and 41b and the mounting holes 42a and 42b are respectively disposed at the same height, when the rotor 42 rotates, the cradle 41 and the wafers n rotate parallel to the rotational direction A of the rotor 42.
For loading and removing items to be dried with respect to the cradle 41, the cradle 41 is pivoted through 90.degree. about the mounting holes in the direction of arrow B.
However, in the conventional downflow spin dryer described above, because the cradle 41 is mounted parallel to the rotational direction A of the rotor 42, the wafers n also rotate parallel to the rotational direction A of the rotor. As a result, the amount of air sucked in through the air inlet 43 along with the rotation of the rotor 42 is small and the drying efficiency is not good.